Iodine During Pregnancy: Are You Getting Enough?

Updated: March 17, 2015

Davide Illini/Stocksy

Around the world, 18 million babies are born mentally disabled every year because of maternal iodine deficiency. While iodine deficiency is rare in the U.S., there are a few things you should know to protect your baby.

Iodine is a mineral found in food — and one of the most important minerals a fetus needs for brain development and physical growth. While our bodies require only the teeny-tiniest amount of it (only 5g over the course of a 70-year lifetime!), that little bit is really important. Iodine deficiency in pregnancy is the most preventable cause of intellectual disability in the world, according to the Centers for Disease Control and Prevention. It's a rare problem in the U.S., but it's a growing problem.

In the past, home-cooked meals with iodized table salt provided adequate iodine in the average American's diet. But iodine content in many of the foods and beverages we consume today is pretty low. The addition of iodine to table salt isn't mandatory in the U.S., and the salt that's used in baked goods, chips and other processed foods isn't iodized either. So with more processed and prepared foods making up our diets, we're getting less iodine. What's more, sea salt isn't iodized either — and many people use sea salt when cooking these days without realizing it doesn't offer the same health benefits as iodized salt.

For these reasons, the American Academy of Pediatrics (AAP) issued new iodine recommendations in 2014 for pregnant and breastfeeding women. The AAP now recommends pregnant and lactating women cook with iodized salt and take a daily supplement with 150 mcg of iodine to reach a total of 290 mcg per day.

Why Is Iodine Important?

During pregnancy, iodine maintains normal function of the thyroid, a gland in the base of your neck that regulates the hormones controlling your metabolism, heart rate, body temperature and other core body functions. Getting enough ensures that your baby develops a healthy and normal thyroid, too. In the rare case a fetus has an underdeveloped thyroid, it can lead to low IQ, developmental delays, deafness, birth defects, cretinism (severely stunted physical and developmental growth) and (in the most extreme cases) death.

Iodine is also key in lactation, as you pass iodine on to your baby through your breast milk. That means the iodine you consume continues to support your baby's thyroid and brain development until your baby begins eating solids.

What About Prenatal Vitamins?

You may get sufficient iodine from your prenatal. But then again, you might not: Recent research has shown that only 15 to 20 percent of pregnant women take a prenatal supplement that contains iodine.

Getting Iodine in Your Diet

Besides checking the label of your prenatal vitamin to ensure it contains iodine, the best way to ensure you're getting enough is by eating a healthy pregnancy diet. In addition to cooking with salt that says "iodized" on the label (1/4 tsp provides 71 mcg), there are plenty of whole foods that are also natural sources of iodine. A few:

Baked cod (99 mcg in 3 oz)

Plain yogurt, low-fat (75 mcg in 1 cup)

Milk, low-fat (56 mcg in 1 cup)

Fish sticks (54 mcg in 3 oz)

Enriched bread (45 mcg 2 slices)

Shrimp (35 mcg in 3 oz)

Enriched macaroni (27 in 1 cup boiled)

Egg, large (24 mcg in one)

Canned tuna (17 mcg in 3 oz)

Creamed corn (14 mcg in 1/2 cup)

Cheddar cheese (12 mcg in 1 oz)

Dried prunes (13 mcg in five)

Raisin bran cereal (11 mcg in one cup)

Lima beans, boiled (8 mcg in 1/2 cup)

Apple juice (7 mcg in 1 cup)

While seaweed can be a good source of iodine, levels can vary widely — from 16 to 2,984 mcg in a 1-oz serving. As long as you aren't allergic, it's likely OK to include some seaweed occasionally in your diet. But it's best not to take a seaweed supplement, since the amount companies list on labels isn't regulated.

The AAP also recommends that pregnant and breastfeeding women also avoid nitrates, and one reason why is because they can impact your body's ability to absorb iodine. Nitrates are found in processed foods and meats including hot dogs, deli meat and sausages (look for "nitrate-free" on the label to ensure it's not in the foods you're eating).

Can You Overdo Iodine?

Yes, you can. The National Institutes of Health recommends that you consume no more than 1,100 micrograms of iodine daily; more can cause hypothyroidism and has even been linked to thyroid cancer. So while taking a prenatal supplement containing iodine with 150 mcg is okay, most doctors don't recommend taking a separate iodine supplement, since most start at 500 mcg.

Are You Getting the Right Amount?

There is no blood test to check iodine levels. If you're worried, talk about it with your doctor, who may want to do a special 24-hour urine collection test, the best way to test iodine levels in the body. But more than likely, she'll say you're fine.

From the What to Expect editorial team and Heidi Murkoff, author of What to Expect When You're Expecting. Health information on this site is based on peer-reviewed medical journals and highly respected health organizations and institutions including ACOG (American College of Obstetricians and Gynecologists), CDC (Centers for Disease Control and Prevention) and AAP (American Academy of Pediatrics), as well as the What to Expect books by Heidi Murkoff.